JP2013201831A - Charging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging device that is capable of achieving reduction in an amount of ripple ascribable to deterioration with time of components or the like and continuing to supply a stabilized DC output voltage to a battery.SOLUTION: A charging device, which includes a control circuit 20 for controlling switch means of a DC/DC converter circuit and charges a battery, further includes: a measurement circuit for measuring an AC current or an AC voltage generated in the DC/DC converter circuit as an AC signal. The control circuit 20 includes: a control amount calculation part 21 for calculating an on/off control amount for the switch means; a storage part 23 in which ideal waveform data of the AC signal is stored; a correction amount determination part 22 for determining, based on a difference between measurement data for one cycle of the AC signal measured by the measurement circuit and the ideal waveform data, a correction amount for each measurement value and storing the correction amount in the storage part 23; and a duty ratio calculation part 24 for calculating a duty ratio by adjusting the on/off control amount using the correction amount stored in the storage part 23.

Description

  The present invention relates to a charging device that converts an AC voltage supplied from an AC power source into a DC voltage and supplies the DC voltage to a battery.

  In general, a charging device includes a rectifying / smoothing circuit that rectifies and smoothes an AC voltage supplied from an AC power source to generate a DC input voltage, and DC / DC that switches the DC input voltage to a DC output voltage by switching the DC input voltage with a switch unit. A converter circuit and a control circuit for controlling the duty ratio of the switch means are provided, and the battery is charged with a DC output voltage obtained by the DC / DC converter circuit.

  The DC / DC converter circuit includes an inverter unit composed of switching means, a transformer connected to the inverter unit on the primary side, and an output unit connected to the secondary side of the transformer.

  By the way, in such a charging device, a ripple may be included in the DC output voltage. If ripples are included in the DC output voltage, it becomes impossible to supply a stable DC output voltage to the battery, which affects the life of the battery and consequently places an excessive maintenance cost burden on the user. For this reason, in the charging device, it is necessary to reduce the amount of ripple (hereinafter, ripple amount) in the DC output voltage.

  As a method for reducing the ripple amount in the DC output voltage, a feed-forward control method for controlling the duty ratio of the switch means according to the ripple amount in the DC input voltage has been conventionally known (for example, Patent Document 1). reference).

  In this conventional method, when the DC input voltage increases, the duty ratio is decreased, while when the DC input voltage decreases, the duty ratio is increased to reduce the ripple amount in the DC output voltage. .

JP 2008-29089 A

  However, since the conventional method controls the duty ratio of the switch means in accordance with the ripple amount of the DC input voltage, the ripple amount that does not appear in the DC input voltage is increased or decreased, for example, the time of the components constituting the inverter unit There is a problem that the DC output voltage becomes unstable because it cannot cope with the increase or decrease in the ripple amount of the DC output voltage or the DC output current due to the deterioration.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to reduce the amount of ripple caused by deterioration of components over time and to continue to supply a stable DC output voltage to the battery. It is in providing the charging device which can do.

In order to solve the above problems, a charging device according to the present invention includes a rectifying / smoothing circuit that rectifies and smoothes an AC voltage to generate a DC input voltage, and converts the DC input voltage to a DC output voltage by switching the DC input voltage using a switch. Charging to charge a battery with a DC output voltage, including a DC / DC converter circuit that performs, a synchronization detection circuit that outputs a synchronization signal at a timing when the polarity of the AC voltage is inverted, and a control circuit that controls the duty ratio of the switch means A device,
A measuring circuit for measuring an alternating current or an alternating voltage generated in the DC / DC converter circuit as an alternating current signal;
The control circuit
A control amount calculation unit that calculates an on / off control amount of the switch means by feedback control so that a value related to the charging state becomes a desired value;
A storage unit storing ideal waveform data for at least one cycle of an AC signal;
Each of the measurement data based on the difference between the measurement data for one period of the AC signal measured a plurality of times by the measurement circuit and the ideal waveform data after the synchronization signal is output until the next synchronization signal is output. A correction amount determining unit that determines a correction amount for each measurement value and stores the correction amount for one cycle of the AC signal in the storage unit;
A duty ratio calculation unit that calculates the duty ratio by adjusting the on / off control amount with the correction amount stored in the storage unit;
It is characterized by having.

According to this configuration, the correction amount is determined based on the difference between the measurement data for one cycle of the AC signal and the ideal waveform data, and the duty ratio is calculated by adjusting the on / off control amount with the correction amount. When the ripple amount increases due to deterioration of the components over time, a correction amount that cancels the ripple amount is determined, and a duty ratio corresponding to the correction amount is calculated.
Therefore, according to this configuration, it is possible to reduce the amount of ripple caused by deterioration of components over time and to continue supplying a stable DC output voltage to the battery.

In addition, the “value relating to the charging state” in the present specification includes the direct current output current, the direct current output voltage or the direct current output power output from the DC / DC converter circuit, the alternating current generated in the DC / DC converter circuit, It also includes AC voltage or AC power, and values (SOC value, battery voltage, etc.) included in battery data.
The “difference between measurement data and ideal waveform data” in this specification includes not only the difference between measurement data and ideal waveform data but also the ratio (ratio) between measurement data and ideal waveform data.

In the above charging apparatus, a new correction amount for one cycle of the AC signal is determined by the correction amount determination unit in a state where the correction amount for one cycle of the AC signal is stored in the storage unit, and is stored in the storage unit. If the difference between the correction amount and the new correction amount is greater than or equal to the specified value,
The correction amount determination unit replaces the correction amount stored in the storage unit with a new correction amount,
The duty ratio calculation unit preferably calculates the duty ratio by adjusting the on / off control amount with a new correction amount stored in the storage unit.

  According to this configuration, when the component deteriorates with time and the ripple amount increases, or when the ripple amount temporarily increases due to a temperature rise or the like, the on / off control amount is adjusted with the new correction amount. Since the duty ratio is calculated, a stable DC output voltage can be continuously supplied to the battery.

  For example, when the ripple amount of the direct current output current output from the DC / DC converter circuit is equal to or greater than a predetermined value, (2) the direct current output from the DC / DC converter circuit. When the phase of fluctuation of the output current is shifted from the target phase of the DC output current by a predetermined value or more, or (3) at the start of charging, a new correction amount can be determined by the correction amount determination unit.

In addition, the DC / DC converter circuit in the charging device includes an inverter unit that generates a primary AC voltage by switching a DC input voltage using switch means, and a transformer that converts the primary AC voltage into a secondary AC voltage. And an output unit that rectifies and smoothes the secondary side AC voltage to generate a DC output voltage,
The AC signal is preferably a primary AC current or a primary AC voltage output from the inverter unit.

  Generally, since the transformer in the charging apparatus is a step-up type, the primary side of the transformer has a lower voltage than the secondary side. Therefore, according to the above configuration for measuring the primary AC current or the primary AC voltage as an AC signal, a relatively inexpensive measurement circuit can be used instead of an expensive measurement circuit having a high withstand voltage.

  ADVANTAGE OF THE INVENTION According to this invention, while aiming at reduction of the ripple amount resulting from a time-dependent deterioration of components, etc., the charging device which can continue supplying a stable DC output voltage to a battery can be provided.

It is a block diagram of the charging device which concerns on this invention. It is a block diagram of a control circuit in the present invention. It is a flowchart which shows the process of the control amount calculation part in this invention. It is a figure for demonstrating the correction table in this invention, Comprising: (a) is a waveform diagram of a synchronizing signal, (b) is a waveform diagram of the ideal waveform data and measurement data of the primary side alternating current of a transformer, (c). FIG. 4 is a diagram illustrating an example of a correction table. It is a flowchart which shows the process of the correction amount determination part in this invention.

  Hereinafter, a preferred embodiment of a charging device according to the present invention will be described with reference to the accompanying drawings.

[Configuration of charging device]
FIG. 1 is a block diagram of a charging device 1 according to an embodiment of the present invention.
As shown in the figure, the charging device 1 is a vehicle-mounted charging device mounted on an electric vehicle, and rectifies and converts an AC voltage supplied from an AC power source 2 such as a commercial AC power source (AC 100 V, 50 Hz / 60 Hz). A rectifying / smoothing circuit 4 for smoothing and generating a DC input voltage, a DC / DC converter circuit 6 for switching the DC input voltage by the switch means 5a to 5d to convert it to a DC output voltage to be supplied to the battery 3A, and a DC output And a control circuit 20 that controls the duty ratio of the switch means 5a to 5d so that the product of the voltage and the DC output current supplied to the battery 3A (DC output power) becomes a predetermined target power value.

  The rectifying / smoothing circuit 4 includes a diode bridge 9 and an electrolytic capacitor (smoothing capacitor) 10 having a capacitance of several hundreds μF to several thousand μF. The rectifying / smoothing circuit 4 preferably includes a power factor improving unit (not shown).

  The DC / DC converter circuit 6 is connected to an inverter unit 5 including four switch means 5a to 5d such as IGBT and MOSFET, a transformer 7 whose primary side is connected to the inverter unit 5, and a secondary side of the transformer 7. Output unit 8. The output unit 8 includes a diode bridge 11 and an LC low-pass filter including a coil 12 and a smoothing capacitor 13.

  In the DC / DC converter circuit 6, the primary side AC voltage is generated from the DC input voltage by the inverter unit 5, the primary side AC voltage is boosted by the transformer 7 and converted into the secondary side AC voltage, and the output unit 8 A DC output voltage is generated from the secondary AC voltage.

In addition, the charging device 1 according to the present embodiment is supplied from the AC circuit 2 and the measurement circuit 14 that measures the primary AC current (corresponding to the “AC signal” of the present invention) output from the inverter unit 5. DC detection based on the battery data transmitted via the CAN communication line from the synchronization detection circuit 15 that outputs a synchronization signal at the timing when the polarity of the AC voltage is inverted, and the battery control unit (EV-BCU) 3B that monitors the battery 3A. And a target power value setting circuit 16 for setting a target power value of the output power.
The battery data includes the current value of the DC output current supplied to the battery 3A, the voltage value of the DC output voltage, the SOC value of the battery 3A, the temperature of the battery 3A, and the like. Usually, since the battery 3A has an extremely low resistance, the DC output voltage is almost equal to the battery voltage.

  The primary AC current value measured by the measurement circuit 14, the synchronization signal output from the synchronization detection circuit 15, the target power value set by the target power value setting circuit 16, and the battery control unit 3B transmitted. The battery data is input to the control circuit 20.

[Configuration of control circuit]
FIG. 2 is a block diagram of the control circuit 20.
As shown in the figure, the control circuit 20 includes, for example, a microcomputer and a program executed thereon, and includes a control amount calculation unit 21, a correction amount determination unit 22, a storage unit 23, and a duty ratio calculation unit. 24 and PWM signal generation means 25. The control amount calculation unit 21 is a controller that performs feedback control such as PID control and observer control so that the value related to the charging state becomes a desired value.
The control circuit 20 in the present embodiment is characterized in that the on / off control amount is adjusted by a correction amount described later determined by the correction amount determination unit 22.

The control amount calculation unit 21 receives the synchronization signal output from the synchronization detection circuit 15, the target power value set by the target power value setting circuit 16, and the battery data transmitted from the battery control unit 3B. A command signal for the control amount and correction amount determination unit 22 is output.
The on / off control amount is a duty ratio of the switch means 5a to 5d when the ripple (for example, ripple current) included in the output (for example, DC output current) from the output unit 8 is not taken into account. It was generated by control.

  Further, the control amount calculation unit 21 includes a current table indicating ideal current values for one cycle of the secondary AC current output from the secondary side of the transformer 7 when the on / off control amount is not adjusted by the correction amount. Are stored in advance. This ideal current value is a current value of a sinusoidal secondary AC current whose amplitude is normalized to 1. The secondary AC current and the DC output current have a certain relationship. For example, if the current value of the DC output current is known, the current value of the secondary AC current can be estimated from the current table. Note that the “sine wave” in this specification includes not only a so-called sine wave but also a cosine wave.

FIG. 3 is a flowchart showing processing executed by the control amount calculation unit 21.
As shown in the figure, when the battery data, the target power value, and the synchronization signal are read in the control amount calculation unit 21 (S1), the direct current output current fluctuation included in the battery data is used to detect the direct current. The ripple amount in the output current is calculated (S2).

If the calculated ripple amount is equal to or greater than a predetermined value set in advance (YES in S3), a command signal for causing the correction amount determining unit 22 to output the correction amount is output from the control amount calculating unit 21 (S4). . Further, the control amount calculation unit 21 calculates the target current value of the DC output current from the target power value and the current voltage value of the DC output voltage included in the battery data, and the ideal current corresponding to the target current value from the current table. The value is inferred, and the current value of the secondary AC current is inferred from the current value of the DC output current included in the battery data. Then, an on / off control amount is calculated by feedback control based on the ideal current value and the current value of the secondary AC current (S5).
On the other hand, if the ripple amount is smaller than a predetermined value set in advance (NO in S3), the on / off control amount is calculated by the feedback control without outputting a command signal to the correction amount determining unit 22. (S5).
The calculated on / off control amount is output to the duty ratio calculation means 24 in synchronization with the synchronization signal.

With reference to FIG. 2 again, the correction amount determination unit 22 which is a characteristic part of the present invention will be described.
As shown in the figure, the correction amount determination unit 22 uses the command signal output from the control amount calculation unit 21 as a trigger, based on the synchronization signal and the current value of the primary AC current measured by the measurement circuit 14. A correction amount for canceling the ripple amount in the DC output current is determined.
Further, the correction amount determination unit 22 generates a correction table 2 stored as the correction table 1 in the storage unit 23.

As shown in FIG. 4, the correction table 2 is measured by the measurement circuit 14 a plurality of times (in this embodiment, 200 times) from when the synchronization signal is output until the next synchronization signal is output. The ratio calculated for each measurement point (t _{1 to} t ₂₀₀ ) based on the measured value (current value) for one cycle of the side AC current and the current value of the ideal waveform data stored in advance in the storage unit 23 (The ratio of the amplitude of the measured current value to the amplitude of the current value of the ideal waveform data) and the correction amount (reciprocal of the ratio) are shown.
The ideal waveform data indicates a current value for one cycle of the primary AC current when a DC output current matching the target current value is output from the output unit 8. The waveform of the ideal waveform data is a sine wave, and the storage unit 23 stores a plurality of ideal waveform data corresponding to the frequency of the AC voltage supplied from the AC power supply 2. Note that the ideal waveform data whose amplitude is normalized to 1 is stored in the storage unit 23, and the ideal waveform data is generated according to the measured amplitude of the primary AC current when the correction table 2 is generated. The amplitude may be adjusted.

FIG. 5 is a flowchart showing processing executed by the correction amount determination unit 22.
As shown in the figure, in the correction amount determination unit 22, when the command signal output from the control amount calculation unit 21 is input, the period after the synchronization signal is output until the next synchronization signal is output. The number of measurements to be measured by the measurement circuit 14 is set (S6). In the present embodiment, the number of measurements is set to 200 in order to generate a current waveform for one cycle of the primary AC current with good reproducibility.
When the number of measurements is set, measurement (reading of the primary AC current value) is started (S7), and when the number of measurements reaches 200, the measurement ends (YES in S8).

When the measurement is completed, a total of 200 measurements, the measurements at t ₁ is arranged in order, it is divided by the current value of the ideal waveform data corresponding to each measurement point (t ₁ ~t _200). Thereby, the ratio between the measured value and the current value of the ideal waveform data is calculated for each measurement point (t _{1 to} t ₂₀₀ ) (S9).
When the ratio is calculated, the correction amount is determined based on the ratio, and the correction table 2 is generated (S10).

Here, even if there is at least one difference between the correction amount of the correction table 1 stored in the storage unit 23 and the correction amount of the correction table 2 (corresponding to the “new correction amount” of the present invention) If the value is greater than or equal to the value (for example, 0.01) (YES in S11), or if the correction table 1 is not stored in the storage unit 23, the correction table 2 is stored in the storage unit 23 as the correction table 1 (S12). ). If the performance degradation can be tolerated, in step S11, the difference between the correction amount of the correction table 1 and the correction amount of the correction table 2 is calculated as an average value of correction amounts (a value obtained by dividing the sum of the correction amounts by the number of measurement points). You may make it judge by whether it is more than a predetermined value.
Then, the correction amount of the correction table 1 newly stored (replaced) in the storage unit 23 is output to the duty ratio calculation means 24 in synchronization with the synchronization signal (S13).
On the other hand, when the difference between the correction amount of the correction table 1 stored in the storage unit 23 and the correction amount of the correction table 2 is less than a predetermined value set in advance (NO in S11), the generated correction table 2 Is discarded, and the correction amount of the correction table 1 stored in the storage unit 23 is output to the duty ratio calculation means 24 in synchronization with the synchronization signal (S13).

Referring to FIG. 2 again, the duty ratio calculation means 24 calculates the duty ratio by multiplying the correction amount output from the correction amount determination unit 22 by the on / off control amount output from the control amount calculation unit 21. The duty ratio is output to the PWM signal generating means 25.
If the ripple amount calculated by the control amount calculation unit 21 is smaller than a predetermined value set in advance (NO in S3 of FIG. 3), the processing of S6 to S13 shown in FIG. The duty ratio is calculated based only on the off control amount.

  The PWM signal generation unit 25 generates a PWM signal based on the duty ratio output from the duty ratio calculation unit 24 and outputs the PWM signal to the inverter unit 5 of the DC / DC converter circuit 6.

  As described above, according to the charging device 1 according to the present embodiment, the correction amount is determined based on the ratio between the measurement data for one cycle of the AC signal and the ideal waveform data (see FIG. 4). Since the duty ratio is calculated by adjusting the on / off control amount, when the ripple amount increases due to deterioration of the components over time, a correction amount that cancels the ripple amount is determined, and according to the correction amount The duty ratio is calculated. Therefore, according to the charging device 1 according to the present embodiment, it is possible to reduce the amount of ripples caused by deterioration of components over time, and to continue supplying a stable DC output voltage to the battery 3A.

  As mentioned above, although preferable embodiment of the charging device which concerns on this invention was described, this invention is not limited to the said embodiment.

In the control amount calculation unit 21 in the above embodiment, the ripple amount in the DC output current is compared with a predetermined value set in advance, and a command signal is output to the correction amount determination unit 22 (S3 in FIG. 3). In place of this, instead of this, when the phase of the fluctuation of the DC output current at a predetermined time (for example, t ₂₀₀ ) deviates from a predetermined target phase by a predetermined value or more, or when the DC output current is a predetermined current A command signal may be output when the phase timing when a value (for example, a peak current value) is deviated from a timing assumed in advance by a predetermined time or more, or the command signal is It may be output.

  Moreover, in the said embodiment, although the current value for 1 period of primary side alternating current is used as ideal waveform data stored in the memory | storage part 23, it replaces with this and is equivalent to 1 period of secondary side alternating current. A current value or a voltage value for one cycle of the primary AC voltage may be used. In these cases, it is necessary to use a measurement circuit 14 that can measure the current value of the secondary AC current and the voltage value of the primary AC voltage.

Furthermore, in the correction amount determination unit 22 in the above embodiment, the correction amount (ratio of the ratio) is calculated based on the ratio calculated based on the measurement value at each measurement point (t _{1 to} t ₂₀₀ ) of the measurement data and the current value of the ideal waveform data. However, the correction amount may be determined from the difference between the measured value and the current value of the ideal waveform data. In this case, the duty ratio calculation means 24 calculates the duty ratio by adding or subtracting the correction amount determined from the difference to the on / off control amount.

  In the above embodiment, the current value of the DC output current and the voltage value of the DC output voltage are acquired based on the battery data transmitted from the battery control unit 3B via the CAN communication line. A detection circuit for detecting the DC output current and the DC output voltage after passing through the included LC low-pass filter may be further provided, and the current value of the DC output current and the voltage value of the DC output voltage may be acquired by the detection circuit.

  Note that the present invention can be applied not only to a vehicle-mounted charging device mounted on an electric vehicle, but also to charging devices in other fields.

DESCRIPTION OF SYMBOLS 1 Charging apparatus 2 AC power supply 3A Battery 3B Battery control unit 4 Rectification smoothing circuit 5 Inverter parts 5a-5d Switch means 6 DC / DC converter circuit 7 Transformer 8 Output part 9 Diode bridge 10 Electrolytic capacitor 11 Diode bridge 12 Coil 13 Smoothing capacitor 14 Measurement circuit 15 Synchronization detection circuit 16 Target power value setting circuit 20 Control circuit 21 Control amount calculation unit 22 Correction amount determination unit 23 Storage unit 24 Duty ratio calculation unit 25 PWM signal generation unit

Claims (6)

A rectifying / smoothing circuit that rectifies and smoothes an AC voltage to generate a DC input voltage, a DC / DC converter circuit that switches the DC input voltage to a DC output voltage by switching the switching means, and the polarity of the AC voltage is inverted. A charging device for charging a battery with the DC output voltage, comprising: a synchronization detection circuit that outputs a synchronization signal at a timing to control; and a control circuit that controls a duty ratio of the switch means,
A measurement circuit for measuring an alternating current or an alternating voltage generated in the DC / DC converter circuit as an alternating current signal;
The control circuit includes:
A control amount calculation unit that calculates an on / off control amount of the switch means by feedback control so that a value related to a charging state becomes a desired value;
A storage unit storing ideal waveform data for at least one cycle of the AC signal;
Based on the difference between the measurement data for one period of the AC signal measured by the measurement circuit a plurality of times from the output of the synchronization signal to the output of the next synchronization signal, and the ideal waveform data A correction amount determining unit that determines a correction amount for each measurement value of the measurement data, and stores the correction amount for one period of the AC signal in the storage unit;
A duty ratio calculation unit that calculates the duty ratio by adjusting the on / off control amount with the correction amount stored in the storage unit;
A charging device comprising: With the correction amount for one cycle of the AC signal stored in the storage unit, a new correction amount for one cycle of the AC signal is determined by the correction amount determination unit and stored in the storage unit. If the difference between the correction amount and the new correction amount is greater than or equal to a predetermined value,
The correction amount determination unit replaces the correction amount stored in the storage unit with the new correction amount,
2. The charging device according to claim 1, wherein the duty ratio calculation unit calculates the duty ratio by adjusting the on / off control amount with the new correction amount stored in the storage unit.   The correction amount determination unit determines the new correction amount when the ripple amount of the DC output current output from the DC / DC converter circuit is equal to or greater than a predetermined value set in advance. Item 3. The charging device according to Item 2.   When the phase of fluctuation of the DC output current output from the DC / DC converter circuit is shifted by a predetermined value or more from the target phase of the DC output current, the correction amount determination unit determines the new correction amount. The charging device according to claim 2 or 3, wherein   The charging device according to claim 2, wherein the new correction amount is determined by the correction amount determination unit at the start of charging. The DC / DC converter circuit includes an inverter unit that switches the DC input voltage by the switch means to generate a primary AC voltage, a transformer that converts the primary AC voltage to a secondary AC voltage, An output unit that rectifies and smoothes the secondary AC voltage to generate the DC output voltage;
The charging apparatus according to claim 1, wherein the AC signal is a primary AC current or the primary AC voltage output from the inverter unit.

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